<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            display: flex;
        }
        .hh{
            width: 600px;
            background-color: #900404;

        }
        .he{
            width: 100px;
            height: 400px;
            background-color: rgb(35, 192, 84);
        }
        .he.a{
            background-color: aqua;

        }
        .he.b{
            background-color: rgb(29, 191, 45);

        }
        .he.c{
            background-color: rgb(97, 31, 195);

        }
    </style>
</head>
<body>
    <div class="hh">
        <div class="he a">1</div>
        <div class="he b">2</div>
        <div class="he c">3</div>
    </div>
</body>
</html>